ANS:A - 160 mH

Formulae for inductance L.
1/L = 1/L1 + 1/L2 + 1/L3.

Therefore substituting the given values in formulae,
1/L = 1/600 + 1/300 + 1/800.
L.C.M of 600, 300, 800 is 2400.

SO
1/L = 4/2400 + 8/2400 + 3/2400.
1/L = 15/2400.

THEREFORE L = 2400/15.
= 160 -> Answer